Pressure sealing method for headspace modification

ABSTRACT

A container cap ( 80 ) positioned within a sealing chamber ( 84 ) has an openable aperture to allow the increase in pressure in the container headspace ( 231 ) before the aperture is resealed. In alternative embodiments the container ( 1 ) may include vacuum compensation panels ( 801, 802,803, 804 ) in its sidewall and/or base.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to a method of light-weighting containers by modifying the pressure in the headspace and a container utilising that method. The pressure modification may be undertaken either during the sealing of the container, or after sealing the container. This headspace modification may be achieved by filling a container with a liquid, sealing the contents of the container from contamination from outside air, and adjusting the pressure of the headspace either during the capping process or after the container has been capped or sealed. The headspace modification process increases the volume of content within the container, thereby increasing the internal pressure within the container. This action in turn may displace the liquid below the headspace in the upper neck region of the container downwardly prior to or after capping of the container, providing for increased top-load capability for the container. This invention may further relate to hot-filled and pasteurized products packaged in heat-set polyester containers.

BACKGROUND

Most production facilities are searching for ways to reduce costs as a small savings on the cost of each single container, for a food or beverage packer, this quickly adds up to tremendous savings, based on the large number of containers processed. Utilizing lighter weight containers or reducing utility costs are good savings methods.

However, lighter weight containers for noncarbonated products can collapse when stacked unless special handling requirements are satisfied. One typical method used to increase stacked weight capability, or top-load strength, in cold fill containers is to dose the container with liquid nitrogen prior to capping. When dosed into a container, liquid nitrogen will provide some internal pressure, which allows the containers to be stacked several pallets high. Gaseous nitrogen is one utility used in the food and beverage industry to expel oxygen from products and increase shelf life.

However, as the nitrogen disperses immediately upon injection the process for controlling accurate dosing is limited. Some of the nitrogen will escape prior to capping, thus rendering the process inexact in terms of absolute pressurisation control. Additionally, handling nitrogen systems can be costly and dangerous.

Nitrogen consumption can be reduced by as much as 80% using a liquid nitrogen dosing system instead of gaseous nitrogen tunnels, but as the capping or sealing of the container occurs at ambient pressure at the precise time of sealing, in both systems, the resulting pressure value is compromised. At the instantaneous moment of sealing, the pressure value can only be equal to ambient pressure. Following capping there is a subsequent rise in internal pressure as the nitrogen continues to expand but cannot escape the sealed container. However, as the nitrogen is dosed prior to sealing there is a loss of some of the nitrogen dose prior to sealing, the amount of which varies according to many factors. This leaves the process inexact in terms of identifying the dose actually in the container after sealing. It is accepted that this will always be a value less than the dose introduced to the open container prior to sealing.

Because air is composed of 78% nitrogen by volume, nitrogen is abundant. Liquid nitrogen has a boiling point of −320° F. (−196° C.) at atmospheric pressure. Handling liquid nitrogen when pressurizing or inerting food and beverage containers on a production line poses challenges. To use liquid nitrogen injection, a production facility must have a storage vessel, liquid nitrogen piping and an injection device capable of metering small amounts of liquid nitrogen accurately and consistently. To store, transfer or inject liquid nitrogen, insulated equipment is a necessity because liquid nitrogen will boil away rapidly when exposed to room temperatures.

The use of nitrogen, however, does provide for a build-up of internal pressure within a container following capping. This is more practical in the case of beverages filled into the container cold, than when used in conjunction with hot fill beverages. In both cases it is possible that all dosed nitrogen disperses prior to sealing the container, for example if there is a stoppage on the line post dosing and prior to capping. However, in a cold filled application the result would be a container that at least is capped at ambient pressure and will remain at ambient pressure. While the benefit of increased top load and sidewall strength would be lost, the result is not particularly damaging as the container would still look attractive to the consumer when purchased. In the case of a hot filled beverage, however, an insufficient dose results in the container being sealed at ambient pressure and possessing little ability to pressurize the container following sealing. As the liquid contents of the container subsequently cool and contract a vacuum will build and the container will distort as a result. This is not attractive for the consumer. Additionally, the dosing process becomes even more difficult to control in the hot fill environment, particularly at fast line speeds. When nitrogen is introduced into a container under ambient pressure conditions and on top of a heated liquid, the nitrogen will be much more volatile than if the liquid is cold. It will disperse much more quickly prior to capping or sealing leaving the consistency of dose, much more uncertain. A stoppage in the line is therefore more damaging to consistency of dose. For this reason, containers are often overdosed as a precautionary measure, and this is still not ideal.

Plastic bottles need to be pressurized at all line speeds, and if control over the exact pressure achieved inside a container is compromised then the speed of the system will also be compromised in order to correctly pressurise each container.

Food and beverage plant personnel are required to consider a number of goals and criteria when selecting a liquid nitrogen system, including:

-   -   Consistent container pressures or consistent oxygen reduction.     -   Plant personnel safety.     -   Reliable system operation.     -   Reasonable acquisition and operating costs.

Each producer has different priorities for each goal, but safety usually is high on the list. It is important to remember that liquid nitrogen becomes a gas at room temperature and expands to 700 times its volume as a liquid. Adequate piping system and injection equipment protection, including safety relief valves, must be used to prevent over-pressurization or equipment rupture. A safety relief valve must be placed between any two shutoff valves in the system. On bulk tank-fed systems, the lowest rated relief device typically is placed outdoors. If a safety relief valve does relieve, it is safer if it happens outdoors rather than inside where someone could get hurt.

Reliability is important on a production line where losses are calculated in minutes of downtime. A liquid nitrogen dosing device will need some startup time from a room temperature condition because all internal surfaces must be cooled down to liquid nitrogen temperatures. As with any liquid nitrogen equipment, operating procedures must be adhered to because the danger of contaminating the equipment with moisture does exist. Moisture is the biggest enemy of the cold surfaces of liquid nitrogen equipment. It takes only a small amount to freeze up the equipment internally. Equipment adjustments such as nozzle changes for different container sizes and maintenance must be able to be completed without moisture contamination or long downtimes. Each production facility has different specifications for liquid nitrogen delivery. Some applications require that the liquid nitrogen be delivered aseptically. In such a case, the dosing unit also must be capable of being sterilized.

Consistent pressurizing or inerting results are important to the entire operation. A water bottle with too little pressure could collapse when stacked or not labelled properly. A bottle with too much pressure possibly could burst when stored in the trunk of a car due to temperature effects. Inerted products could oxidize or spoil if the liquid nitrogen dose was too small; too large a dose on an inerted product could cause an over-pressurized container to jam the production line. Nitrogen injection can be accomplished by dosing individual containers or with a steady stream of liquid nitrogen. Either method can yield consistent results.

Liquid nitrogen will boil away rapidly once it is introduced into a container. Therefore, it is important to control the liquid nitrogen efficiently before dosing. A typical 18 fl oz (600 ml) polyethylene terephthalate (PET) bottle with a 1 fl oz (30 ml) headspace and pressure specification of 17 psig will need approximately 0.001411 oz (0.04 g) of liquid nitrogen. The dose of liquid nitrogen will boil away and expand to 1.163 fl oz (34.4 ml) of room temperature nitrogen gas after the container is sealed. Add 1.163 fl oz of gas to a sealed volume of 1 fl oz, and you end up with 17 psig.

The challenge for the liquid nitrogen dosing equipment manufacturer is to control the boiling liquid and deliver the 0.001411 oz consistently at speeds from 40 bottles/min to more than 1,000 bottles/min. The dosing equipment can control the liquid nitrogen up to the dosing point, but it cannot control the liquid nitrogen's behavior once it has been dosed into the container. The liquid nitrogen will boil away rapidly as the container travels to the capper or seamer, so travel time should be minimized for accurate results. The transfer from dosing to capping also should be smooth to prevent the boiling liquid from bouncing out of the container.

Another aspect to consider is consistent container fill levels. If container headspace varies because the fill levels are wildly different, the final bottle pressures also will be wildly different. For example, suppose the bottle previously mentioned had an 18 fl oz fill with a 1 fl oz headspace, and the next bottle on the production line had a fill of 18.3 fl oz (610 ml) with a 0.6 fl oz (20 ml) headspace. Both bottles receive a 0.001411 oz charge of liquid nitrogen. The liquid nitrogen dosing is consistent; however, in accordance with basic gas laws, the final bottle pressure on the 18 fl oz fill is 17 psig and the bottle with a 18.3 fl oz fill has 25.5 psig final pressure. Many factors determine final bottle pressure accuracy in addition to the dosing equipment accuracy. They include container volume consistency and good sealing closures. All factors must be addressed for good results.

Costs are a critical concern for manufacturers. It is important to remember that initial purchase price, installation expenses and operating costs must be considered jointly. Outside bulk storage tank vessels are more expensive to obtain than small portable dewars, but liquid nitrogen costs much less in bulk than dewars. The changing out process also adds to the hidden cost of using dewars; a 41.6 gal (160 l) dewar usually will last one 8-hr shift on a production line.

Piping is another area where processors try to save money. Most manufacturers can make a relatively inexpensive foam-insulated pipe. However, consider how much liquid nitrogen is lost during one year with a foam insulated pipe. Acquisition and installation costs are higher for a vacuum-jacketed system, but the reduced loss rate due to superior insulation makes operating costs lower than with a foam-insulated system. An inexpensive foam insulated liquid nitrogen injection device is not a bargain if downtime due to a frozen dosing device occurs.

Some dosing devices require a thaw out period of up to 24 hr after use. Startup and shutdown times also are important factors to consider when calculating liquid nitrogen injection system operating costs. When considering liquid nitrogen dosing on a production line, it is necessary to look at many factors. Initial cost is only a small part of the puzzle. Most production plants considering using liquid nitrogen need the proper information and training to be successful and should consult a liquid nitrogen dosing equipment-manufacturer before making a final decision.

The amount of liquified gas added to a container and the head-space volume above the product filled into the container are critical elements in determining the resulting internal pressure of a container upon expansion of the liquified gas. Also, the temperature of hot filled products affects the internal pressure after cooling, according to Boyles law.

Conventionally, the dosage of liquified gas dispensed into a container is based on an average expected fill level of the containers in a continuous fill operation. Using this method, any variation in head-space volume due to variations in fill level would cause under and over pressurized containers. U.S. Pat. No. 4,662,154 discloses the art of providing a closed loop control circuit between a liquid nitrogen dispenser and a pressure detector. The average internal pressure of recently sealed containers is monitored to adjust the dosage of liquid nitrogen added to containers being presently dosed. Containers not meeting the preset pressure range may be rejected.

Problems of uniform pressurization still remain using this method due to basing the dosage on the average pressure of already sealed containers. Whether a given container has a head-space volume that varies high or low, it will receive a dosage based upon an average head-space volume of containers previously sealed. Therefore, the range of container pressures can still vary widely.

Additional problems are caused by the fact that container pressure is the only monitored dosage criteria. Container pressure is measured after a container has already received a dosage and is sealed. This after-the-fact detection can result in high spoilage rates when there are sudden variations in product fill level. These sudden variations will not be detected until after the containers are sealed. Even more spoilage may result as the detection and correction of improper dosages is slow due to the averaging process. Containers must continue to be incorrectly dosed until the average values detect fluctuation.

All of the abovementioned concerns are even greater when used with hot filling liquids into containers.

So called ‘hot fill’ containers are well known in prior art, whereby manufacturers supply PET containers for various liquids which are filled into the containers and the liquid product is at an elevated temperature, typically at or around 85 degrees C. (185 degrees F.).

The container is manufactured to withstand the thermal shock of holding a heated liquid, resulting in a ‘heat-set’ plastic container. This thermal shock is a result of either introducing the liquid hot at filling, or heating the liquid after it is introduced into the container.

Once the liquid cools down in a capped container, however, the volume of the liquid in the container reduces, creating a vacuum Within the container. This liquid shrinkage results in vacuum pressures that pull inwardly on the side and end walls of the container. This in turn leads to deformation in the walls of plastic bottles if they are not constructed rigidly enough to resist such force.

Typically, vacuum pressures have been accommodated by the use of vacuum panels, which distort inwardly under vacuum pressure. Prior art reveals many vertically oriented vacuum panels that allow containers to withstand the rigors of a hot fill procedure. Such vertically oriented vacuum panels generally lie parallel to the longitudinal axis of a container and flex inwardly under vacuum pressure toward this longitudinal axis.

In addition to the vertically oriented vacuum panels, many prior art containers also have flexible base regions to provide additional vacuum compensation. Many prior art containers designed for hot-filling have various modifications to their end-walls, or base regions to allow for as much inward flexure as possible to accommodate at least some of the vacuum pressure generated within the container.

Even with such substantial displacement of vacuum panels, however, the container requires further strengthening to prevent distortion under the vacuum force.

The liquid shrinkage derived from liquid cooling, causes a build up of vacuum pressure. Vacuum panels deflect toward this negative pressure, to a degree lessening the vacuum force, by effectively creating a smaller container to better accommodate the smaller volume of contents. However, this smaller shape is held in place by the generating vacuum force. The more difficult the structure is to deflect inwardly, the more vacuum force will be generated. In prior art proposals, a substantial amount of vacuum may still be present in the container and this tends to distort the overall shape unless a large, annular strengthening ring is provided in horizontal, or transverse, orientation typically at least a ⅓ of the distance from an end to the container.

The present invention relates to hot-fill containers and may be used by way of example in conjunction with the hot fill containers described in international applications published under numbers WO 02/18213 and WO 2004/028910 (PCT specifications) which specifications are also incorporated herein in their entirety where appropriate.

The PCT specifications background the design of hot-fill containers and the problems with such designs that were to be overcome or at least ameliorated and in particular the use of pressure compensation elements.

A problem exists when locating such transversely oriented panels in the container side-wall, or end-wall or base region, even after vacuum is removed completely from the container when the liquid cools down and the panel is inverted. The container exits the filling line just above a typical ambient temperature, and the panel is inverted to achieve an ambient pressure within the container, as opposed to negative pressure as found in prior art. The container is labelled and often refrigerated at point of sale.

This refrigeration provides further product contraction and in containers with very little sidewall structure, so-called ‘glass look-a-like’ bottles, there may therefore be some panelling that occurs on the containers that is unsightly. To overcome this, an attempt is made to provide the base transverse panel with more extraction potential than is required, so that it may be forced into inversion against the force of the small headspace present during filling. This creates a small positive pressure at fill time, and this positive pressure provides some relief to the situation. As further cool down occurs, for example during refrigeration, the positive pressure may drop and may provide for an ambient pressure at refrigerated temperatures, and so avoid panelling in the container.

This situation is very hard to engineer successfully, however, as it depends on utilising a larger headspace in order to compress at base inversion time, and it is less desirable to introduce a larger headspace to the container than is necessary in order to retain product quality.

While it is desirable to have the liquid level in the container drop, to avoid spill when opened by the consumer, it has been found that providing too much positive pressure potential within the base may cause some product spill when the container is opened, particularly if at ambient temperatures.

In most filling operations, containers are generally filled to a level just below the containers highest level, at the top of the neck finish.

Maintaining as small a container headspace as possible is desirable in order to provide a tolerance for subtle differences in product density or container capacity, to minimize waste from spillage and overflow of liquids on a high-speed package filling line, and to reduce container contraction from cooling contents after hot fill.

Headspace contains gases that in time can damage some products or place extra demands on container structural integrity. Examples include products sensitive to oxygen and products filled and sealed at elevated temperatures.

Filling and sealing a rigid container at elevated temperatures can create significant vacuum forces when excessive headspace gas is also present.

Accordingly, less headspace gas is desirable with containers filled at elevated temperatures, to reduce vacuum forces acting on the container that could compromise structural integrity, induce container stresses, or significantly distort container shape. This is also true during pasteurization and retort processes, which involve filling the container first, sealing, and then subjecting the package to elevated temperatures for a sustained period.

Those skilled in the art are aware of several container manufacturing heat-set processes for improving package heat-resistant performance. In the case of the polyester, polyethylene terephthalate, for example, the heat-setting process generally involves relieving stresses created in the container during its manufacture and to improve crystalline structure.

Typically, a polyethylene terephthalate container intended for a cold-fill carbonated beverage has higher internal stresses and less crystalline molecular structure than a container intended for a hot-fill, pasteurized, or retort product application. However, even with containers such as described in the abovementioned PCT specifications where there is little residual vacuum pressure, the neck finish of the container is still required to be very thick in order to withstand the temperature of fill.

My PCT patent specification WO 2005/085082 describes a previous proposal for a headspace displacement method which is incorporated herein in its entirety where appropriate by way of reference.

Where reference in this specification is made to any prior art this is not an acknowledgment that it forms part of the common general knowledge in any country or region.

OBJECTS OF THE INVENTION

In view of the above, it is an object of one possible embodiment of the present invention to provide a container and contents combination having an increased pressure within an unsealed container whereby the volume of the contents combination exceeds the volume of the as-moulded container, said container having an increased pressure when subsequently sealed or capped.

It is a further object of one possible embodiment of the present invention to provide a container, cap and contents combination that provides for an increased pressure within a sealed container whereby the volume of the contents combination is larger than the contents combination initially filled and sealed within the container, when the contents combination is held at the temperature used at the time of filling and sealing the container.

It is a further object of the present invention to force additional contents into the container under controlled pressure to reinforce the sidewalls.

In view of the above, it is an object of one possible embodiment of the present invention to provide a pressure sealing method and headspace modification method that can provide for increased pressure within the sealed container such that there is increased top load capability.

It is a further object of one possible embodiment of the present invention to provide a pressure sealing method and headspace modification method that can provide for increased pressure within the sealed container such that there is increased top load capability, utilising a gas other than nitrogen such as simple clean or filtered air.

It is a further object of one possible embodiment of the present invention to provide a pressure sealing method and headspace modification method that can provide for removal of vacuum pressure such that there is substantially no remaining force within the container utilising a gas other than nitrogen, such as simple clean or filtered air.

It is a further object of one possible embodiment of the present invention to provide a pressure sealing method and headspace modification method that can provide for removal of vacuum pressure such that there is substantially no remaining force within the container utilising a simple heated liquid such as water.

It is a further object of one possible embodiment of the present invention to provide a headspace compression method whereby air, or some other gas or liquid or combination thereof, is charged into the headspace under sealed pressure to create an increased pressure in order to negate the effect of vacuum pressure created during cooling of the product.

It is a further object of one possible embodiment of the present invention to provide a headspace modification method whereby sterile or heated liquid, or air, or some other gas or combination thereof, is charged into the headspace under sterile conditions to create a positive pressure in order to negate the effect of vacuum pressure created during cooling of the product.

It is a further object of one possible embodiment of the present invention to provide a headspace modification method whereby sterile air, or some other gas or liquid or combination thereof, is charged into the headspace under sealed pressure to negate the effect of vacuum pressure created during cooling of the product.

It is a further object of one possible embodiment of the present invention to provide a headspace modification method whereby a compressive seal is applied to the neck finish of the container.

It is a further object of one possible embodiment of the present invention to provide a headspace displacement method whereby a compressive seal is applied to the neck finish that is forcibly displaceable into the container prior to cooling the liquid contents, such that a positive pressure may be induced into the container.

A further and alternative object of the present invention in all its embodiments, all the objects to be read disjunctively, is to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

The pressure sealing method of the present invention may provide for the seal of a container to be finally closed within an increased pressure environment rather than at ambient pressure. In this way an exact pressure can be achieved within the container at the moment of sealing, ensuring consistency of headspace pressure in every container. This prevents any variability caused by inconsistent timing of bottle presentation to a capper, inconsistent fill levels within a container, inconsistent container sizes and so forth.

The present invention may improve upon dosing techniques for expanding gases such as nitrogen, by ensuring the seal is finalised only when the correct dose is applied inside the container.

The present invention may also provide for the use of non-expanding gases to be used, such as air, filtered air, steam or other inert gas.

The present invention may also provide for fluid or liquid to be introduced under pressure into the headspace of a container as opposed to expanding or non-expanding gas. The liquid may be either, heated and contractible or heatable and non-contractable.

The present invention may be suitable for cold filled and aseptic filling lines as a way of controlling nitrogen dosing into containers for increased top load to ensure consistent dose application.

The present invention may be suitable for cold filled and aseptic filling lines as a way of increasing top load in containers but avoiding the use of nitrogen by instead increasing the pressure within containers through the introduction of some other medium, for example filtered air or water, which may be sterile and/or heated and/or cold.

The present invention may provide for the pressure to be increased within the container immediately prior to and during capping.

The present invention may provide for the pressure re-sealing of a container that has been initially sealed in a conventional, ambient pressure manner.

The present invention may provide for pressurisation of the container to provide compensation for any cooling of heated contents within the container, either before or after the contents have cooled.

The pressure sealing method of the present invention may provide for on-line gaseous or liquid dosage calibration in a conventional container filling line. The amount of pressure within the headspace may be controlled precisely at the time of sealing and may be readily adjusted to deliver consistent dosage to each container which corresponds to the container's individually measured head-space volume.

The system may generally include an empty container in-feed station, a continuous container conveying system, a container product fill station, a container head-space dosing station, an optional liquified gas dispensing station, an optional gas dispensing station, an optional liquid dispensing station, a container sealing station, a container internal pressure sensing station, a discharge conveyor and a reject apparatus.

One preferred embodiment of the present invention may provide for the container sealing station to incorporate the optional gas, liquefied gas, liquid and container internal pressure sensing stations.

The system may provide for the on-line control of the head-space volume of each container after it has been filled with product and following the addition of liquid or gas. The head-space volume measurement may be precisely controlled at the time of sealing so that the dosage of liquid or gas delivered to each container may correspond directly to its individually measured head-space, and generally does not alter once immediately sealed, except for variations caused by temperature changes within the contained liquid.

With dosages being exactly correlated to the individually measured requirements of each container, very uniform pressure ranges may be obtained opposed to dosages based on expected fill levels or after-the-fact average measurements. Therefore, containers can be down gauged as they will not be required to accommodate a wide pressure range. Furthermore, the system may achieve lower spoilage rates due to improperly pressurized containers because the system immediately self adjusts for fill variations as containers receive a dosage of liquid or gas.

A particular advantage of the present method and system may be the greater and more precise control allows for much lower pressure dosing for hot fill containers. In prior methods a minimum pressure value can only be assured by over pressurisation on average, such that the lowest dose achieved will meet specifications. This has resulted in generally high pressures achieved during the early stages of hot fill, when the container is hot and malleable. As a result the container is stressed significantly in most occasions, necessitating the need for example for petaloid bases and container designs more suitable to carbonated or pressure vessels. This reduces significantly the design options available for containers, and requires additional weight in the container surrounding the base in order to achieve reasonable results.

Other advantages and aspects of the invention will become apparent upon making reference to the specification, claims, and drawings to follow.

According to one aspect of the present invention there is provided a container for use in hot or cold filling operations and having a seal or cap adapted to provide a temporary opening or aperture into said container, said opening or aperture providing for the introduction under pressure of one or more liquids and/or gases, said seal or cap providing with a neck of said container, in use, a container headspace having a pressure, substantially at the moment of sealing, greater than existed prior to introduction of said one or more liquids and/or gases.

According to a further aspect of the present invention there is provided an expandable container having a seal or cap that is applied to the container under an increased pressure environment such that the container headspace has a positive pressure value substantially at the exact moment of sealing to provide for increased pressure inside the container.

According to a further aspect of the present invention there is provided a container having a seal or cap that is applied to the container under an increased pressure environment such that the container headspace has a positive pressure value substantially at the exact moment of sealing to provide for increased pressure inside the container to negate the effects of a subsequent cooling of a liquid that is heated either before or after filling into the container.

According to a further aspect of the present invention there is provided a container having a seal or cap that is finally closed on a container under a controlled environment such that the container headspace has a controlled pressure value substantially at the exact moment of sealing to provide for increased pressure inside the container to negate the effects of a cooling of a liquid that is heated either before or after filling into the container.

According to a further aspect of the present invention there is provided a capping unit that seals the open end of a container from the outside environment and applies pressure to the inside of the container prior to and during application of a cap or seal such that the container headspace has a positive pressure value substantially at the exact moment of sealing to provide for increased pressure inside the container.

According to a further aspect of the present invention there is provided a capping unit that seals the open end of a container from the outside environment and applies pressure to the inside of the container prior to and during application of a cap or seal such that the container headspace has a positive pressure value substantially at the exact moment of sealing to provide for increased pressure inside the container to negate the effects of a subsequent cooling of a liquid that is heated either before or after filling into the container.

According to a further aspect of the present invention there is provided a container having a seal or cap having a temporary opening or aperture into said container, said aperture providing for the introduction under pressure of a gas, or liquid or both, said aperture also being sealable under compression to provide a controlled raising of internal pressure within the container prior to cooling of the heated contents.

According to a further aspect of the present invention there is provided a container having a seal or cap temporarily applied such that an opening or aperture into said container is provided by an incomplete seal being formed between the cap and the neck finish of the container, said aperture providing for the introduction under pressure of a gas, or liquid or both, said aperture also being sealable under torque compression to provide a controlled raising of internal pressure within the container prior to cooling of the heated contents.

According to a further aspect of the present invention there is provided a container having a seal or cap providing a temporary seal immediately post-filling and an aperture or opening being accessible under sterile conditions to provide for the introduction of a heated or sterile gas, or liquid or both, said aperture or opening also further being sealable under sterile conditions to provide a controlled raising of internal pressure within the container following cooling of the heated contents.

According to a further aspect of the invention a method of filling a container with a liquid includes introducing the liquid through an open end of the container, providing a seal or cap having, or adapted to have, an opening or aperture, providing at least one gas and/or liquid through the opening or aperture and sealing the opening or aperture to increase the pressure in a headspace of the container.

According to a further aspect of the invention a method of filling a container with a fluid includes introducing the fluid through an open end of the container so that it, at least substantially, fills the container, heating the fluid before or after its introduction into the container, providing a seal or cap having an opening or aperture, said opening or aperture being initially sealed, providing for the heated contents to cool, providing a method of subsequently accessing the opening or aperture under controlled conditions and injecting gas and/or liquid through the opening or aperture and sealing the opening or aperture under controlled conditions, so as to compensate for the pressure reduction in the headspace of the container following the cooling of the heated contents.

According to a further aspect of the present invention there is provided a container having an upper portion with an opening into said container, said upper portion having a neck finish adapted to include, subsequent to the introduction of a heated or heatable liquid into the container, a moveable seal, said seal being inwardly compressible or mechanically moveable while the liquid is in a heated state, or prior to heating, so as to increase the pressure of the headspace.

According to a further aspect of the invention a method of filling a container with a fluid includes introducing the fluid through an open end of the container so that it, at least substantially, fills the container, heating the fluid before or after its introduction into the container, providing a moveable seal for the open end to cover and contain the fluid, said seal being capable of mechanical compression of the headspace of the container so as to compensate for subsequent pressure reduction in a headspace of the container under the seal as the heated contents are cooled.

According to a further aspect of the invention a method of sealing a container with a gas or liquid includes capping the container with the entire capping station being pressurised.

Further aspects of the invention which should be considered in all its novel aspects will become apparent from the following description.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 a-b: show a container according to one embodiment of a Prior Art invention with a mechanically compressible cap applied to seal the beverage;

FIGS. 2 a-b: shows a container according to a further embodiment of a Prior Art invention with a mechanically compressible cap applied to seal the beverage;

FIGS. 3 a-b: show part cross-sectional view of an alternative embodiment of the compressed cap of FIGS. 1 and 2;

FIGS. 4 a-b: show a container according to a one embodiment of the invention with an enlarged view of a cap including a sealable aperture;

FIG. 5 a-c: show enlarged views of one possible embodiment of the cap of FIGS. 4 a-b;

FIG. 6 a-c: show one embodiment of enclosing the cap of FIGS. 5 with a pressure application device;

FIGS. 7 a-c: show one embodiment of a cap-sealing device suitable for use in the pressure application device of FIGS. 6;

FIGS. 8 a-c: show the embodiment of cap-sealing device of FIGS. 7 closing the cap while under compression;

FIGS. 9 a-c: show withdrawal of the cap-sealing device of FIGS. 8 following sealing and subsequent decompression of the compression chamber;

FIGS. 10 a-c: show the container cap of FIGS. 9 following release from the compression chamber (container not shown fully);

FIG. 11 a-c: show enlarged views of a further embodiment of the cap of FIGS. 4 a-b;

FIGS. 12 a-c: show one embodiment of a cap-sealing device suitable for use in the sterilising application device of FIGS. 11;

FIGS. 13 a-c: show one embodiment of cap-sealing device of FIGS. 12 piercing the cap while under sterilisation;

FIGS. 14 a-c: show withdrawal of the piercing and delivery device of FIGS. 13 following sterilisation and subsequent pressure equalisation of the headspace;

FIGS. 15 a-c: show the resealing of the container cap of FIGS. 14 prior to container release from the sterilisation chamber (container not shown fully);

FIGS. 16 a-c: show additional views of the cap of FIGS. 12,13,14,15 according to one possible method of headspace modification;

FIGS. 17 a-c: show a further possible embodiment of this invention;

FIGS. 18: shows a further possible embodiment of the invention using a sealing chamber;

FIG. 19 a-b: show a possible embodiment of the invention in the form of a capping machine;

FIG. 20 a-b & FIGS. 21 a-b: show a further possible embodiment of the invention using a pressure chamber;

FIG. 22 a-c & FIGS. 23 a-c: show diagrammatically a possible method of the present invention;

FIGS. 24 to 27: show diagrammatically a further possible embodiment of the invention in the form of a capping machine;

FIGS. 28 a-d, 29 a-d & FIGS. 30 a-b: show further embodiments of the invention using a sealing chamber;

FIG. 31: shows diagrammatically a possible capping system; and

FIGS. 32 a-c; 33 a-c 34 a-c; 35 a-c; 36 a-c; and 37 a-c: shows various possible embodiments with alternative forms of vacuum compensation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following description of preferred embodiments is merely exemplary in nature, and is in no way intended to limit the invention or its application or uses.

As discussed above, to accommodate vacuum forces during cooling of the contents within a heat set container, containers have typically been provided with a series of vacuum panels around their sidewalls and an optimized base portion. The vacuum panels deform inwardly, and the base deforms upwardly, under the influence of the vacuum forces. This prevents unwanted distortion elsewhere in the container. However, the container is still subjected to internal vacuum force. The panels and base merely provide a suitably resistant structure against that force. The more resistant the structure the more vacuum force will be present. Additionally, end users can feel the vacuum panels when holding the containers.

Typically at a bottling plant the containers will be filled with a hot liquid and then capped before being subjected to a cold-water spray resulting in the formation of a vacuum within the container that the container structure needs to be able to cope with. The present invention relates in one embodiment to hot-fill containers and a method that provides for the substantial removal or substantial negation of vacuum pressure. This allows much greater design freedom and light weighting opportunity as there is no long& any requirement for the structure to be resistant to vacuum forces that would otherwise mechanically distort the container.

As seen in a Prior Art solution in FIGS. 1 a to b, when hot liquid 21 is introduced to a container 1, the liquid occupies a volume that is defined by a first upper level 3 a. Should a compressive cap 8 be applied immediately post fill to a container neck 2, then a vacuum builds up in the headspace 23 b that is above the liquid and under the sealing surface 10 of the compressive cap, the sealing surface being the lower border of the compressible inner chamber 9 which is engaged with the outer portion of the cap 8. This headspace vacuum is normally only released when the cap is removed. While the cap 8 remains in place then the vacuum force remains largely unchanged. If the walls of the container bend or flex inwardly then the vacuum pressure level may drop to a small degree.

Referring to FIGS. 3 a-b shows a further embodiment of Prior Art invention.

However, as disclosed in the Prior Art as illustrated in FIGS. 2 a-b, mechanical compression of the moveable seal within the cap structure to achieve a positive pressure occurs only once the container has cooled. This has the distinct disadvantage of moving unsterilized wall surfaces of the cap components into communication with the liquid contents of the container. This contamination can not be tolerated and so an embodiment of the present invention provides only for this mechanical compression of the headspace to occur immediately post application of the cap.

In this way mechanical compression can achieve a positive pressure while the contents of the container are in a heated state, and to subsequently enable the container to be cooled without panelling. The cap components that enter the container headspace under compression will be sterilised therefore by the heated contents prior to cooling. It will be appreciated that many different structures are envisaged for providing a primary sealing structure that is forcible downwards to displace the liquid contents to a large degree. Containers of the 600 ml size for example will require displacement to the order of 20-30 cc of liquid. Containers of the 2000 ml range of size will require displacement to the order of 70 cc of liquid.

It is envisaged that the cap 8 may be of metal or plastics and could in alternative embodiments be pushed into the neck of the container 1 rather than screwed and could be lockable in a required position.

The cap 9 may be controllably displaced downwardly by any suitable mechanical or electrical or other means, or manually.

The method of the present invention allows many variables in mechanical compression to be accounted for, but for larger containers where significant downward displacement would be required it is envisaged that only some of the compressive force would be obtained from a compressive cap and, more significantly, the remainder would be obtained by the methods discussed in the following disclosure.

Referring to FIGS. 4 a and b, an exemplary embodiment of the present invention is shown with a cap 80 engaged with the container neck 2. Figures onward from 4 a all refer to upper portions of containers as similarly shown in FIG. 4 a.

According to a further aspect of the present invention, and referring to FIGS. 4 a and b, and FIGS. 5 a-c, following the introduction of a liquid, which may be already heated or suitable for subsequent heating, a cap may be applied including a small opening or aperture 81. Thus a headspace 23 a is contained under the main cap body 80 and above the fluid level 40 in the container. The headspace 23 a is communicating with the outside air at this stage and is therefore at ambient pressure and allowing for the fluid level 40.

As seen in FIGS. 6 a-c, in one embodiment a sealing chamber 84 is applied over the neck finish and cap combination to seal the liquid from the outside air (the upper, closed end of the structure 84 is not shown). Following the introduction of a compressive force 50, for example by way of injecting air or some other gas, the increased pressure within the sealing chamber provides for a subsequent increase in pressure within the headspace 23 b and also forces the fluid level 40 to a lower point due to the subsequent expansion of the plastic container.

As an alternative to the injection of gas, a heated liquid could be injected, for example heated water. This would provide further advantage, in that the liquid injected would not be subject to the expansion that would normally occur when injecting gas into a heated environment. Thus less force would be ultimately applied to the sidewalls of the container during the early hot-fill stages.

Even further, the injected liquid would contract less than a gas when subsequently cooled. For this reason less liquid is necessarily required to be injected into the headspace to provide compensation for the anticipated vacuum forces that would otherwise occur.

Now referring to FIGS. 7 a-c (the compressive force not shown), while pressure is maintained within the sealing chamber 84, a plug mechanism 82 is moved downwardly from a delivery device 83 towards the aperture 81.

As can be seen in FIGS. 8 a-c, while pressure is maintained within the sealing chamber 84, the hole is closed off permanently by the placement of the plug 82 into the hole 81.

At this point, and as can be seen in FIGS. 9 a-c, the headspace 23 b is charged under a controlled pressure, dependant on the amount of gas delivered, and the sealing chamber may provide for withdrawal of the delivery device 83 following a release of pressure within the chamber as the container is ejected and returned to the filling line.

As shown in FIGS. 10 a-c, as the bottle subsequently travels down the filling line and is cooled, the headspace 23 b expands as the liquid volume shrinks. The fluid level 40 lowers to a new position 41 and the pressurised headspace 23 b expands and loses some or all of its pressure as it forms a new headspace 23 c.

Importantly, however, once the contents are cooled there is no residual vacuum in the container.

As an alternative, and as shown in FIGS. 10 d-f, the plug 92 may be temporarily attached to the cap, for example by member 91, during production of the cap. A liquid, as in the example illustrated, or gas, could be injected in the same manner under pressure to circumnavigate the plug and enter the container headspace under pressure, and a rod mechanism 93 is then forced downwardly to advance the plug 92 into the hole permanently. In this alternative there is no need to load the rod with multiple plug mechanisms.

A further example of such an alternative is provided in FIG. 18. In this embodiment of the invention the cap 80 has a plug 92 temporarily attached by a member (not shown). A sealing chamber 84 encloses the cap and provides an internal sealed chamber headspace 87 through the compression of sealing rings 89 against the upper surface of the cap. Gas or liquid, or, a combination of both, is injected into the chamber headspace 87 through an inlet 86 and through the spaces around the plug into the headspace of the container. Once the required pressure within the container is obtained, the push rod 88 is advanced downwardly to force the plug 92 into position within the cap and therefore seal the container headspace under the required pressure. This provides for a calculated internal pressure to be achieved precisely at the time of sealing the container, when the plug is advanced into final position. This provides for forward compensation of the effects of subsequent vacuum generated by a cooling of any heated contents within the container.

With reference to FIGS. 19 a and 19 b, the present invention may be manufactured to function along very similar lines to a typical capping station on a filling line. A typical capping machine head unit 101 encapsulates the sealing unit 84 and provides the function of sealing and pressurising the container through the cap to seal the container. A typical capping unit may have optionally already torqued the cap into position, but the container would remain unsealed due to the presence of a plug being in an ‘unplugged’ position within the cap and allowing the passage of liquid or gas between the inside and outside of the container. The precise moment of sealing the container occurs as the plug is rammed into position and the headspace within the cap is not at ambient pressure, as would be typical of prior art capping procedures within the filling and capping area, but instead with the present invention a headspace modification unit 102 may receive capped containers 1, and subsequently pressurise the container immediately prior to sealing the container with a cap sealing plug.

As an alternative, the headspace modification unit 102 could also perform the usual function of a typical capping machine. The unit could receive empty containers, apply caps containing the plugs and subsequently torque the caps into position as well as pressurise the container prior to ultimately sealing the container through advancing the plug or some other sealing method.

Still further examples of alternative embodiments of the present invention are illustrated in FIGS. 20 a-f. The cap 80 may incorporate a rubber, or other suitable material, plug 182 within the cap. This would provide the advantage of having an initially leakproof seal to the container prior to pressurising the headspace. In this way, the container could be charged with pressure from a liquid or gas either prior to the cooling of the contents, for example immediately after filling and capping by way of overpressure, or the procedure could occur after the contents have been cooled and there is a vacuum within the container. By way of example, the cap and sealing plug 182 could be sterilized by very heated water 66 after the liquid contents have cooled. This would sterilize the upper surface of the cap and a heated liquid could then be injected to compensate for vacuum pressure. Following withdrawal of the injecting needle 102 the sterilizing heated liquid could be removed as the container is ejected from the pressure chamber. The rubber seal 182 would have closed off and sealed the container to prevent any communication between the headspace under the cap and outside air present as the chamber is opened.

A further alternative for a suitable plug mechanism within a cap 80 is illustrated in FIGS. 21 a-f. A ball-valve type closure 882 could be utilized to provide a hole through which headspace modification may occur within the pressure chamber unit as previously described. Once the headspace has been pressurized, a rotating push rod 883 can close the ball valve while the headspace is maintained under exact pressure as illustrated in FIGS. 21 d-f.

FIGS. 22 a-c shows a typical example method of headspace modification using the method of the present invention. An empty container (not shown below the neck finish) is filled or even ‘overfilled’ to the brim of the neck finish, and a cap is applied that has an opening through which headspace modification can be achieved, for example a ball closure device. The capped neck finish, at least, is contained within a pressure chamber (not shown) and the container is placed under a calculated pressure. This increase in pressure may be by injection of a gas as in the illustrated example, or by overinjection of further liquid. During this process the container will increase in size to a degree allowing the fluid level to drop (if gas is being injected) and the ball-valve closure may then be closed to maintain the increased pressure within the container.

The same method procedure may occur using a more typical ‘push-pull’ type sport closure as illustrated in similar manner in FIGS. 23 a-c.

As a further alternative to the present invention, and to remove the need for a hole or plug mechanism within the cap itself, and with reference to FIGS. 17 a, a normal cap could be applied by a capping unit but not forcibly torqued into position. The neck finish can then be enclosed within the chamber 84 and the liquid or gas forced into the container through the gap between the cap and the thread mechanisms of the neck finish, as shown by passage of liquid 86. Once the desired pressure is obtained the cap, as shown in FIG. 17 b, can then be torqued into position by advancing the torque rod 85 within the chamber 84 while holding the container headspace at pressure. In this embodiment the method may be achieved using standard caps rather than modified caps. FIG. 17 c illustrates removal of the torque rod 85, correctly torqued cap 80, immediately prior to ejecting the container head from the chamber 84.

It will be appreciated that the present invention offers multiple choices in carrying out a headspace modification procedure by way of modifying a typical capping machine. Such a piece of machinery could easily be employed to also provide the function of capping the container in addition to modifying the headspace during the procedure.

FIG. 24 shows how a container could be contained within a typical sealing chamber 84 from immediately below the neck support ring 33 of the container.

FIG. 25 illustrates how the whole container could be contained within a sealing chamber 84. In this embodiment the container will not be stressed from the increased pressure until after ejection from the sealing chamber.

FIG. 26 shows an alternative embodiment of the present invention. It is envisaged that the sealing chamber 84 could comprise optionally a lower end sealing skirt 884. In this example, a sealing ring of soft material may be inflated under pressure of water or gas through an inlet 883 to form a close contact with the container shoulder. Gas or liquid may then be charged into the pressure chamber headspace 87 through inlet 86 to modify the container headspace prior to final sealing.

FIG. 27 shows how the sealing chamber of FIG. 26 could be incorporated into a typical capping unit station with rotary head applicators. This would allow for a modified capping unit to apply a cap in the normal manner, but to modify the headspace prior to application of torque to seal the cap on the container.

In facilitating the present invention, the complete or substantial removal of vacuum pressure by displacing the headspace prior to the liquid contraction now results in being able to remove a substantial amount of weight from the sidewalls due to the removal of mechanically distorting forces.

According to a further aspect of the present invention, and referring to FIGS. 11 a-c, following the introduction of a liquid, which may be already heated or suitable for subsequent heating, a cap may be applied including a small opening or aperture 81 which is temporarily covered by a communicating seal 91. Thus a headspace 23 d is contained under the main cap body 80 and above the fluid level 40 in the container. The headspace 23 d is not communicating with the outside air at this stage and is therefore at typical container pressure during the stages of cooling down on the filling line.

As seen in FIGS. 12 a-c, once the container has been typically cooled to a level providing for labelling and distribution the headspace 23 e will be in an expanded state with a lowered fluid level, and will have created a vacuum due to the contraction of the heated liquid within the container.

As seen in this preferred embodiment of the present invention, in order to remove the vacuum pressure a sealing chamber 84 is applied over the neck finish and cap combination to seal the communicating seal 91 from the outside air (the upper, closed end of the structure 84 is not shown).

Following the introduction of a sterilising medium 66, for example by way of injecting heated water, preferably above 95 degrees C., or a mixture of heated water and steam, the sterilising medium provides for the sterilisation of the internal surfaces of the sealing chamber (84) and the communicating seal 91.

Now referring to FIGS. 13 a-c, while the sterilising medium, is maintained within the sealing chamber 84, a plug mechanism 82 is placed downwardly from a delivery device 83 towards the aperture 81. The plug mechanism pierces the communicating seal 91 and is withdrawn again temporarily as shown in FIGS. 14 a-c, providing for communication between the sterilized volume within the sealing chamber above the cap (80) and the headspace (23 e) below the cap.

As can be seen in FIGS. 14 a-c, the sterilising medium, for example heated water at 95 c, is immediately drawn into the container through the open hole 81 due to the communicating seal being pierced. This causes equalization of pressure or removal of vacuum pressure within the container, such that the level of the headspace 23 f rises higher. In another preferred embodiment the liquid would in fact be injected into the container under a small pressure supplied from the sealing chamber 84 such that the pressure within the container would in fact be a positive pressure and the headspace would in fact be very small.

The integrity of the product volume within the container is not compromised as the environment above the cap has been sterilised prior to communicating with the headspace, and the additional liquid supplied into the container replaces the volume ‘lost’ due to shrinkage of heated liquid within the container prior to the method of headspace replacement described.

Following the pressure equalization, and now referring to FIGS. 15 a-c, the delivery device 83 is advanced again such that the plug 82 will be injected into the hole to close it off permanently. At this point, the headspace 23 f is under a controlled pressure dependent on the volume of liquid having been delivered to compensate for previous liquid contraction, as described above.

The sealing chamber may now provide for withdrawal of the delivery device 83 which may now be done following a release of sterilising medium and/or pressure within the chamber as the container is ejected and returned to the filling line.

It will be appreciated that many variations of sealing chamber may be utilised, for example the sealing chamber may only seal directly to the top surface of the cap, rather than enclosing the entire cap.

It will also be appreciated by those skilled in the art that may forms of seal may be employed to provide the same the temporary seal and also the plug mechanism to be utilised.

Thus a method of compensating vacuum pressure within a container is described. Referring to FIGS. 16 a-c, the original headspace level 40 experienced following cooling of heated contents within a closed container provides for a vacuum to be present within the first headspace 23 d. Following compensation according this embodiment of the present invention the headspace level changes and perhaps rises 41 depending on the pressure contained within the headspace and the pressure within the headspace 23 f is now preferably virtually at ambient pressure or preferably slightly positive such that the sidewalls of the container are supported by the slight internal pressure.

With reference to FIGS. 28 a-d, an alternative embodiment of the present invention also incorporates a compressible cap wherein the compression occurs after filling and prior to the cooling of the contents. In this way, by compression occurring when the liquid is hot, the chamber 9 may be sterilized by the contents once it is advanced into the container. The compressible cap may be contained within a compression chamber as previously described, particularly for large size containers. Containers of the 600 ml size for example will require displacement to the order of 20-30 cc of liquid, but containers of the 2000 ml range of size will require displacement to the order of 70 cc of liquid. Such a large displacement is difficult to achieve without having an extremely large displaceable chamber entering the container. Therefore, in order to keep the chamber size to a minimum, it is envisaged that the compression chamber could provide an injection of a certain amount of gas or liquid, and a compressible cap could provide the rest of the compression required. In this way a minimum of gas is also injected into the container. Of course, for small container sizes it will be appreciated that just the compressible cap could be utilised.

Unlike as described in prior art, the present invention provides for the hot liquid within the container to sterilize the underside of the internally presented surface of the inner chamber 9 as it has been compressed into the hot liquid contents.

Ordinarily, as the product cools, a vacuum will build up within the container in the primary headspace 23 b under the cap. This vacuum may distort the container 1 to a degree if the walls are not rigid enough to withstand the force.

However, as the internal pressure has been adjusted upwardly prior to product cooling, the net effect may be a temporary raised level of pressure during product cooling and substantially no pressure once product cooling has finished, or perhaps even advantageously a small amount of positive pressure.

Referring to FIGS. 29 a-d, another similar embodiment of the present invention provides for a mechanical cap that has a mechanically controllable “out” and “in” position. The compressive cap 8 is applied to the container 1 immediately post filling with a hot beverage. In this particular embodiment the sealing surface 10 of the compressible inner chamber 9 is displaced higher than in the previous example shown in FIGS. 24 a-d.

Referring to FIGS. 30 a-b, a further embodiment of the present invention is disclosed. The cap structure may be either a 2-piece construction, or a single unit whereby the compressible inner chamber 9 engages with an internal thread on the neck finish 99 and causes compression of the headspace as the cap is applied and secured to the container 1. Again, for larger size containers this provides the ability to keep gas or liquid injection to a minimum while utilising the displacement of the hot liquid contents to provide the increase in container pressure as the container is sealed.

Referring to FIGS. 31, a further embodiment of the present invention is disclosed. The disclosed system generally includes an empty container in-feed station prior to the filling station. This may be through preblown containers being fed into the Filling Enclosure, or may be through online blowmolding production as illustrated. In the case of online blowmolding the preforms are fed into an integrated blowmolder that also has its own housing that may be continuously shielded alongside and joining the Filling and Capping Enclosures.

The system may also contain a continuous container conveying system, a container product fill station, a container head-space dosing station, an optional liquified gas dispensing station, an optional gas dispensing station, an optional liquid dispensing station, a container sealing station, a container internal pressure sensing station, a discharge conveyor and a reject apparatus.

Alternatively, as illustrated in FIG. 31 the conveying system, fill station and container sealing station, or capping station, may all be integrally contained within an enclosure or integrated enclosures such that the inside environment may be pressurised. This results in the headspace within each container being pressurised to the desired level as the capper seals the container. Effectively the ambient pressure within the enclosure is artificially elevated while the container is sealed and the internal pressure of the container rises immediately upon ejection of the filled and capped containers as they are presented to a lower ambient pressure outside of the system enclosures.

The system provides for the on-line control of the head-space volume of each container as it is filled with product through elevated ambient pressure around the container opening. The head-space volume measurement is precisely controlled at the time of sealing so that each container corresponds directly to its individually measured head-space, and generally does not alter once immediately sealed, except for variations caused by temperature changes within the contained liquid and ambient temperature or pressure changes.

With dosages being exactly correlated to the individually measured requirements of each container, very uniform pressure ranges are obtained as opposed to dosages based on expected fill levels or after-the-fact average measurements. Therefore, containers can be down gauged as they will not be required to accommodate a wide pressure range. Furthermore, the system achieves lower spoilage rates due to improperly pressurized containers because the system immediately self adjusts for fill variations.

A particular advantage of the present method and system is the greater and more precise control allows for much lower pressure dosing for hot fill containers. In prior methods a minimum pressure value can only be assured by over pressurisation on average, such that the lowest dose achieved will meet specifications. This has resulted in generally high pressures achieved during the early stages of hot fill, when the container is hot and malleable. As a result the container is stressed significantly in most occasions, necessitating the need for example for petaloid bases and container designs more suitable to carbonated or pressure vessels. This reduces significantly the design options available for containers, and requires additional weight in the container surrounding the base in order to achieve reasonable results.

With reference to FIGS. 32 a-c, an alternative embodiment of the present invention also incorporates at least one portion of the sidewall 801 configured to respond to vacuum pressure forces. In this particular embodiment, the amount of gas or liquid required to be forcibly injected into the container 1 within the sealing chamber 84 prior to sealing the cap 800 onto the container is reduced.

When a PET container is filled with liquid at a temperature above 70 degrees Celsius the plastic walls become very soft and elastic as the material passes its elastic modulus. With the subsequent force being applied to the container by introduction of a force to raise internal pressure, the sidewalls expand and the overall volume of the container increases. Some of this increase in volume is non-recoverable and results in the container becoming larger than originally manufactured. A particular object of the present invention is to reduce the amount of stress being applied to the sidewalls to the lowest possible amount to prevent unnecessary volume growth in the container.

This is of particular benefit when utilising very thin sidewalls such as found in lightweight containers. It will be appreciated therefore, that in a particular volume size container to be filled with a heated liquid, for example in a range of 75 to 95 degrees Celsius, then the amount of gas or fluid required to be introduced to compensate for the subsequent contraction of contents may be reduced if the container has a residual capacity to account for a portion of the expected contraction. For example, in a container of 600 cc size, it may be expected that approximately 25-30 cc of fluid contraction may occur and therefore an amount of gas or fluid equivalent to this would need to be injected into the headspace during final sealing of the container in order to compensate. By providing this compensation it may be possible to therefore lightweight the container or change the shape of the container as there is a much reduced need for the container to resist vacuum pressure forces that would otherwise occur.

It will be appreciated that introduction of this additional material creates extra stresses initially on the container. By configuring at least a portion of the sidewall to respond to vacuum forces, it is possible to reduce the amount of initial material introduced, for example to 50% of the required amount, if the sidewalls are able to provide compensation for 50% of the required amount also.

It will be appreciated that a container-that is only required to compensate for 50% of expected vacuum pressure through sidewall compensation will be able to be made more lightweight than a container required to compensate for the entire 100% through sidewall compensation.

With reference to FIGS. 33 a-c an alternative embodiment of the present invention also incorporates at least one transversely oriented pressure panel 802 in the container 1. In this particular embodiment the transverse panel is located in the base portion of the container, but may equally be incorporated in the sidewall. In this particular embodiment, the amount of gas or liquid required to be forcibly injected into the container 1 within the sealing chamber 84 prior to sealing the cap (800) onto the container is also reduced. As explained above with reference to FIGS. 32 a-c, the transverse panel may account for a portion of the required vacuum compensation, for example 40%, when moved into the inverted position as shown in FIG. 33 c from the initial position as shown in FIG. 33 a. Inversion of the element 802 may be by way of mechanical force for example. As the container can account easily for some of the vacuum compensation required, there is only a need to provide for approximately 60% of the required liquid contraction by way of pressure injecting prior to sealing the cap. In this way there is reduced stress applied to the container during processing.

With reference to FIGS. 34 a-c an alternative embodiment of the present invention provides for both sidewall vacuum compensation and transverse panel compensation to be combined with headspace compensation for even less stress to be applied to the container during processing. By way of example, it will be appreciated that if the sidewall compensation elements 801 provide approximately 30% of vacuum compensation, and the transverse panel 802 is able to provide approximately 40% of vacuum compensation, then a charge of gas or liquid into the headspace during sealing would only require approximately 30% of that required in a container not having vacuum compensation elements equivalent to 801 and 802. It will be appreciated that varying amounts of compensation may be attributed to each element.

With reference to FIGS. 35 a-c a further alternative embodiment of the present invention is also provided. In the same way as already described, at least one portion of the sidewall may incorporate a vacuum compensation element 803. In this particular embodiment, the element 803 is also configured to expand radially outwardly under internal pressure as illustrated in FIG. 35 c. It will be appreciated that under internal pressure charge during headspace sealing the vacuum compensation element 803 will reduce the amount of stress within the container by expanding radially outwardly first. If filled with a heated liquid, the contents will subsequently cool inside the container and a pressure reduction will occur. As this happens the element 803 will return to the as moulded position shown in FIG. 35 a and will then, subsequently be able to provide further vacuum compensation. By way of example only, if element 803 as shown in FIG. 35 a is able to provide approximately 30% of the required vacuum, then 70% of the compensation would be required to be introduced during headspace sealing. By incorporating a vacuum compensation element 803 that is able to expand outwardly then the stress induced is reduced during the initial phases by a significant amount.

With reference to FIGS. 36 a-c a further alternative embodiment of the present invention is also provided. It will be appreciated by the prior descriptions above that a container of the present invention may be provided with sidewall vacuum compensation elements or may be provided with sidewall vacuum compensation elements that are able to expand radially outward under pressure to reduce stresses during headspace modification and sealing procedures. These containers may also be provided with transverse pressure panel compensation elements also to further reduce the amount of stress required to be imposed on the container during processing. In this particular embodiment the transverse panel 802 is placed in the base of the container. It is envisaged by way of example and with reference to FIGS. 35 a-c and FIGS. 36 a-c, that element 803 may be able to provide approximately 30% of the required vacuum compensation and base element 802 may provide approximately 30% of the required vacuum compensation. Therefore, 40% of the compensation required would be injected into the headspace during processing as previously described. As sidewall element 803 is able to expand radially outward then the stress imposed during processing and headspace modification is reduced further.

With reference to FIGS. 37 a-c, even further stress reduction is anticipated in a further embodiment of the present invention. In a manner as described above, base element 804 is configured to expand longitudinally outward to relieve the pressure induced during headspace modification and injection of gas or liquid during sealing. This reduces the stresses imposed upon the container sidewall. In this particular embodiment, sidewall element 803 is also configured to expand radially outward under the internal pressure. Therefore substantial ability is provided within the container to reduce the stresses induced as gas or liquid is injected into the container. Upon subsequent cooling of any heated contents inside the container both sidewall element 803 and transverse element 804 are able to be inverted inwardly to assist vacuum pressure compensation.

Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope or spirit of the invention. 

1-12. (canceled)
 13. A sealing machine apparatus for pressurizing the headspace of a filled container while applying a seal, comprising: an apparatus for receiving a plurality of containers; a pressure chamber apparatus connected to a surface or sealing member for engaging a surface on the container or on a cap provided for the container; a source of pressure or dosing system coupled to said pressure chamber for raising the pressure within said pressure chamber and said containers; apparatus for moving the sealing member or surface into engagement with the surface on the container or cap; said pressure chamber surrounding a container sealing apparatus for applying a seal or said cap to at least one of said containers; said container sealing apparatus moving to seal said container within the pressure chamber while the pressure chamber is subjected to a raised internal pressure to create an increased pressure within the sealed container.
 14. An apparatus as claimed in claim 13, wherein said sealing machine is a capping machine, and said seals are said caps or are closures.
 15. An apparatus as claimed in claim 13, wherein said containers are filled with a heated liquid.
 16. An apparatus as claimed in claim 13, wherein said sealing machine is a rotary device driven by a rotatable driven turret.
 17. An apparatus as claimed in claim 16, wherein said containers are moved about in a generally circular path by said turret.
 18. An apparatus as claimed in claim 13, wherein said pressure chamber provides temporary sealing of said containers adjacent a neck finish of said containers.
 19. An apparatus as claimed in claim 18, wherein said container sealing apparatus or said pressure chamber provides temporary sealing of said containers at or adjacent a neck support ring of said neck finish.
 20. An apparatus as claimed in claim 13, wherein said container sealing apparatus is a holding apparatus for holding the cap in position to engage a finish of the container.
 21. An apparatus as claimed in claim 13, wherein said container sealing apparatus provides capping torque to close the container.
 22. An apparatus as claimed in claim 13, wherein said source of pressure or dosing system provides at least one liquid and/or gas.
 23. An apparatus as claimed in claim 22, wherein at least one said liquid and/or gas is steam, air, nitrogen, or carbon dioxide.
 24. An apparatus as claimed in claim 13, wherein said containers are for use in hot or cold filling operations each having a said seal or said cap adapted to provide a temporary opening or aperture into said container, said opening or aperture providing for the introduction under pressure of one or more liquids and/or gases, said seal or cap providing with a neck of said container, in use, a container headspace having a pressure, at the moment of sealing, substantially greater than existed prior to introduction of said one or more liquids and/or gases.
 25. An apparatus as claimed in claim 24 further including at least one vacuum compensation element in a sidewall of the container.
 26. An apparatus as claimed in claim 24 or claim 25 including at least one vacuum compensation element in a base of the container.
 27. An apparatus as claimed in claim 24 including at least one expandable element in a sidewall of the container.
 28. An apparatus as claimed in claim 24 or claim 27 including at least one expandable element in a base of the container.
 29. An apparatus as claimed in claim 24 wherein said greater pressure, substantially at the moment of sealing, is positive.
 30. An apparatus as claimed in claim 24 for hot filling wherein, after hot filling, the greater pressure compensates for a pressure reduction on cooling of the contents of the container.
 31. An apparatus as claimed in claim 24 wherein said seal or cap is adapted to provide said opening or aperture after said seal or cap has been applied to the neck.
 32. An apparatus as claimed in claim 24 wherein said seal or cap is adapted to be pierced to provide said opening or aperture and expose the container headspace to ambient pressure.
 33. A cap for a container, the cap being adapted for use with the apparatus of claim
 13. 34. A system for filling a container with a fluid including introducing the fluid through an open end of the container, providing a seal or cap, providing a sealing chamber enclosing an opening or aperture between said seal or cap and said container interior, increasing the pressure within the sealing chamber by introducing at least one liquid and/or gas through the opening or aperture to create an increased pressure within the headspace of the container, sealing the opening or aperture within the sealing chamber under the increased pressure conditions.
 35. A system for filling a container as claimed in claim 34, in which the fluid is heated before or after its introduction into the container, and said system compensates for subsequent pressure reduction in a headspace of the container under the seal or cap following the cooling of the heated contents.
 36. A system as claimed in claim 34 in which the at least one liquid and/or gas passes through the opening or aperture under pressure.
 37. A system as claimed in claim 34 in which the container is positioned in a pressurizing area.
 38. A system as claimed in claim 34 in which the at least one liquid and/or gas is a heated liquid or steam injected through the opening or aperture.
 39. A system as claimed in claim 34 in which the opening or aperture is provided with a temporary or partial seal through which the at least one liquid and/or gas is provided.
 40. A system as claimed in claim 35 including conveying said sealed or capped containers prior to the pressure chamber, and creating and/or providing said opening or aperture within the pressure chamber.
 41. A system as claimed in claim 40 in which the opening or aperture provided within said seal or cap is provided with a temporary or partial seal for at least a period of time prior to conveyance into said pressure chamber.
 42. A system as claimed in claim 41 in which said seal or cap has a liner material on an inside surface, said liner temporarily sealing the opening or aperture.
 43. A system as claimed in claim 40 in which the opening or aperture is sealed under elevated pressure conditions.
 44. A system as claimed in claim 34 or 40, wherein said container includes at least one moveable pressure panel in a sidewall of said container.
 45. A system as claimed in claim 40, wherein said container includes at least one moveable pressure panel in a base of said container.
 46. A container when filled by the system of claim
 40. 47. A method of filling and processing a container with a fluid including: introducing the fluid through an open end of the container so that it, at least substantially, fills the container, applying a seal or cap to said container, transporting or conveying said container, creating and/or providing an opening or aperture in said seal or cap, providing a method of introducing at least one liquid and/or gas through the opening or aperture at a pressure greater than within said container prior to providing said opening or aperture, providing a method of sealing the opening or aperture.
 48. A method as claimed in claim 47 wherein said seal or cap is subjected to at least partial sterilization treatment prior to the provision of said opening or aperture. 